Part 1. Solubility in the (NH4)3PO4-H3PO4-Ca3(PO4)2-H2O system with the ratio NH3/H3PO4 = 0.5.

Solution number

t/°C

Chemical1

102 * Mass Fraction w1

Chemical2

102 * Mass Fraction w2

Chemical3

102 * Mass Fraction w3

Chemical4

102 * Mass Fraction w4

Chemical5

102 * Mass Fraction w5

Chemical6

102 * Mass Fraction w6(b)

Solid Phase(s)(c)

1

45

CaO

1.33

NH3

1.24

P2O5

9.88

H2O

87.55

H3PO4

13.6

H2O

83.79

A

2

45

CaO

1.62

NH3

1.80

P2O5

14.77

H2O

81.81

H3PO4

20.40

H2O

76.18

“

3

45

CaO

1.84

NH3

2.41

P2O5

19.64

H2O

76.11

H3PO4

27.12

H2O

68.63

“

4

45

CaO

2.10

NH3

3.01

P2O5

24.56

H2O

70.33

H3PO4

33.91

H2O

60.98

“

5

45

CaO

2.32

NH3

3.68

P2O5

29.35

H2O

64.65

H3PO4

40.53

H2O

53.47

A + B

6

45

CaO

2.49

NH3

4.21

P2O5

34.13

H2O

59.17

H3PO4

47.13

H2O

46.17

A + B + C

7

45

CaO

2.44

NH3

4.79

P2O5

39.06

H2O

53.71

H3PO4

53.94

H2O

38.83

B + C

8

45

CaO

1.91

NH3

5.47

P2O5

44.22

H2O

48.40

H3PO4

61.06

H2O

31.56

“

9

45

CaO

1.17

NH3

6.06

P2O5

49.35

H2O

43.42

H3PO4

68.15

H2O

24.62

“

10

45

CaO

0.50

NH3

6.73

P2O5

54.72

H2O

38.05

H3PO4

75.56

H2O

17.21

“

11

60

CaO

0.89

NH3

1.26

P2O5

9.91

H2O

87.96

H3PO4

13.7

H2O

84.19

A

12

60

CaO

1.26

NH3

1.82

P2O5

14.81

H2O

82.11

H3PO4

20.45

H2O

76.47

"

13

60

CaO

1.57

NH3

2.41

P2O5

19.69

H2O

76.33

H3PO4

27.19

H2O

68.83

"

14

60

CaO

1.75

NH3

3.03

P2O5

24.56

H2O

70.66

H3PO4

33.91

H2O

61.31

"

15

60

CaO

2.07

NH3

3.62

P2O5

29.38

H2O

64.93

H3PO4

40.57

H2O

53.74

A + B

16

60

CaO

2.30

NH3

4.21

P2O5

34.20

H2O

59.29

H3PO4

47.23

H2O

46.26

"

17

60

CaO

2.52

NH3

4.79

P2O5

37.04

H2O

55.65

H3PO4

51.15

H2O

41.54

"

18

60

CaO

2.39

NH3

5.45

P2O5

43.92

H2O

48.24

H3PO4

60.65

H2O

31.51

A + B + C

19

60

CaO

1.61

NH3

6.05

P2O5

49.19

H2O

43.15

H3PO4

67.92

H2O

24.42

B + C

20

60

CaO

0.83

NH3

6.71

P2O5

54.54

H2O

37.92

H3PO4

75.31

H2O

17.15

"

21

75

CaO

0.68

NH3

1.24

P2O5

9.93

H2O

88.15

H3PO4

13.7

H2O

84.37

A + B

22

75

CaO

0.99

NH3

1.82

P2O5

14.86

H2O

82.33

H3PO4

20.52

H2O

76.67

"

23

75

CaO

1.24

NH3

2.41

P2O5

19.75

H2O

76.60

H3PO4

27.27

H2O

69.08

"

24

75

CaO

1.38

NH3

3.03

P2O5

24.69

H2O

70.90

H3PO4

34.09

H2O

61.50

"

25

75

CaO

1.81

NH3

3.53

P2O5

29.45

H2O

65.21

H3PO4

40.67

H2O

53.99

"

26

75

CaO

2.01

NH3

4.22

P2O5

34.30

H2O

59.47

H3PO4

47.36

H2O

46.41

"

27

75

CaO

.2.07

NH3

4.92

P2O5

39.17

H2O

53.84

H3PO4

54.09

H2O

38.92

"

28

75

CaO

2.43

NH3

5.44

P2O5

43.87

H2O

48.26

H3PO4

60.58

H2O

31.55

"

29

75

CaO

2.09

NH3

6.02

P2O5

49.68

H2O

42.21

H3PO4

68.60

H2O

23.29

B + C

30

75

CaO

1.36

NH3

6.67

P2O5

54.25

H2O

37.72

H3PO4

74.91

H2O

17.06

"

31

90

CaO

0.55

NH3

1.24

P2O5

9.94

H2O

88.27

H3PO4

13.7

H2O

84.48

A + B

32

90

CaO

0.80

NH3

1.83

P2O5

14.88

H2O

82.49

H3PO4

20.55

H2O

76.82

"

33

90

CaO

1.04

NH3

2.42

P2O5

19.77

H2O

76.77

H3PO4

27.30

H2O

69.24

"

34

90

CaO

1.26

NH3

3.04

P2O5

24.69

H2O

71.01

H3PO4

34.09

H2O

61.61

"

35

90

CaO

1.45

NH3

3.65

P2O5

29.56

H2O

65.34

H3PO4

40.82

H2O

54.08

"

36

90

CaO

1.75

NH3

4.23

P2O5

34.39

H2O

59.63

H3PO4

47.49

H2O

46.53

"

37

90

CaO

1.87

NH3

4.83

P2O5

39.17

H2O

54.13

H3PO4

54.09

H2O

39.21

"

38

90

CaO

2.22

NH3

5.46

P2O5

44.00

H2O

48.32

H3PO4

60.76

H2O

31.56

"

39

90

CaO

2.40

NH3

6.00

P2O5

48.83

H2O

42.77

H3PO4

67.43

H2O

24.17

"

40

90

CaO

1.51

NH3

6.67

P2O5

54.17

H2O

37.65

H3PO4

74.80

H2O

17.02

B + C

Part 2. The compiler has used the data in Part 1 to calculate the following molalities.

Solution number

Chemical1

m1 [mol/kg]

Chemical2

m2 [mol/kg]

Chemical3

m3 [mol/kg]

Chemical4

m4 [ ]

Chemical5

m5 [ ]

Mole Fraction6

1

CaO

0.283

NH3

0.870

H3PO4

1.66

2

CaO

0.379

NH3

1.39

H3PO4

2.732

3

CaO

0.478

NH3

2.06

H3PO4

4.032

4

CaO

0.614

NH3

2.90

H3PO4

5.675

5

CaO

0.774

NH3

4.05

H3PO4

7.745

6

CaO

0.962

NH3

5.36

H3PO4

10.42

7

CaO

1.12

NH3

7.25

H3PO4

11.47

8

CaO

1.08

NH3

10.2

H3PO4

19.74

9

CaO

0.847

NH3

14.5

H3PO4

28.24

10

CaO

0.52

NH3

23.0

H3PO4

44.80

11

CaO

0.19

NH3

0.66

H3PO4

1.66

12

CaO

0.294

NH3

1.40

H3PO4

2.729

13

CaO

0.407

NH3

2.06

H3PO4

4.031

14

CaO

0.509

NH3

2.91

H3PO4

5.645

15

CaO

0.687

NH3

3.96

H3PO4

7.703

16

CaO

0.886

NH3

5.35

H3PO4

10.42

17

CaO

1.08

NH3

6.78

H3PO4

12.56

18

CaO

1.35

NH3

10.2

H3PO4

19.64

19

CaO

1.18

NH3

14.6

H3PO4

28.39

20

CaO

0.86

NH3

23.0

H3PO4

44.82

21

CaO

0.14

NH3

0.864

H3PO4

1.66

22

CaO

0.23

NH3

1.40

H3PO4

2.731

23

CaO

0.322

NH3

2.05

H3PO4

4.029

24

CaO

0.401

NH3

2.90

H3PO4

5.657

25

CaO

0.598

NH3

3.84

H3PO4

7.685

26

CaO

0.772

NH3

5.35

H3PO4

10.41

27

CaO

0.948

NH3

7.43

H3PO4

14.18

28

CaO

1.37

NH3

10.1

H3PO4

19.59

29

CaO

1.60

NH3

15.2

H3PO4

30.06

30

CaO

1.42

NH3

23.0

H3PO4

44.81

31

CaO

0.12

NH3

0.863

H3PO4

1.66

32

CaO

0.19

NH3

1.40

H3PO4

2.730

33

CaO

0.268

NH3

2.05

H3PO4

4.023

34

CaO

0.365

NH3

2.90

H3PO4

5.647

35

CaO

0.478

NH3

3.97

H3PO4

7.702

36

CaO

0.671

NH3

5.34

H3PO4

10.41

37

CaO

0.850

NH3

7.24

H3PO4

14.08

38

CaO

1.25

NH3

10.2

H3PO4

19.64

39

CaO

1.77

NH3

14.6

H3PO4

28.46

40

CaO

1.58

NH3

23.0

H3PO4

44.85

Notes: Table 1 a These values were calculated by the compiler. Table 1 b This is the water content of the CaO-NH3H3PO4-H2O system. Table 1 c The solid phases are: A=CaHPO4; B=NH4H2PO4; C=Ca(H2PO4)2·H2O.

Method/Apparatus/Procedure: An isothermal method1 was used. Phosphoric acid neutralized by NH3 to the chosen ratio was placed in round 350 ml vessels and stirred. CaO was then added in small amounts until a steady turbidity appeared. Equilibrium was ascertained by repeated analysis of the liquid phase for Ca. This was done complexometrically using fluorexon as indicator.2 Equilibrium was reached in 4-6 hrs. The composition of the solid phase was determined petrographically and by chemical analysis.

Source and Purity of Materials: Chemically pure H3PO4 and aqueous ammonia and reagent grade CaO were used. The CaO was powdered and sifted through a 0.16 mm mesh sieve.

Estimated Errors: Solubility: No information is given. Temperature: No information is given.